2003MNRAS.341.1268P

The Kα resonance complexes in oxygen ions Oi-Ovi are theoretically computed, and resonance oscillator strengths and wavelengths are presented. The highly resolved photoionization cross-sections, with relativistic fine structure, are computed in the coupled channel approximation using the Breit-Pauli R-matrix method. A number of strong Kα resonances are found to be appreciable, with resonance oscillator strengths f_r> 0.1. The Kα resonance wavelengths of Oi-Ovi lie in the relatively narrow wavelength range 22-23.5 Å, and the X-ray opacity in this region should therefore be significantly affected by K ⟶ L transitions in oxygen. The results should be useful in the interpretation of soft X-ray spectra observed from Chandra and XMM-Newton.